Thermodynamic packer



Sept. 11, 1962 J. E. -rL F 3,053,321

THERMODYNAMIC PACKER Filed NOV. 23, 1959 5 Sheets-Sheet 1 John E.Ortloff Inventor By am...) 5. M Attorney I Sept. 11, 1962 J. E. ORTLOFF3,053,321

THERMODYNAMIC PACKER Filed Nov. 23, 1959 5 Sheets-Sheet 2 7 i 1 5 j 'i:34

I i 1 I n ii a v v V FIG. 4

John E. Ortloff inventor 8. Attorney Sept- 1962 J. E. ORTLOFF 3,053,321

THERMODYNAMIC PACKER Filed Nov. 23, 1959 3 Sheets-Sheet 3 John E.Ortloff Inventor By W 8. Qu-L Attorney 3,653,321 Patented Sept. 11, 19623,053,321 THERMGDYNAMEC PACKER John E. Ortloif, Tulsa, Ulda, assignor toJersey Production Research Company, a corporation of Delaware Filed Nov.23, 1959, Ser. No. 854,654 6 Claims. (Cl. 1o6--l79) The presentinvention relates to apparatus for controlling the flow of fluids inboreholes and more particularly relates to an improved packer assemblywhich can be readily set in place in a borehole or wellbore withoutresort to the hydraulic or mechanical apparatus required to actuatepackers of conventional design. In still greater particularity, theinvention relates to a thermodynamic packer which is actuated in aborehole or wellbore by movement of a bimetallic element responsive tochanges in temperature.

Packers of various types are used in a wide variety of oil fieldoperations. In conjunction with air drilling, for example, they arefrequently set into place on either side of an aquifer in order topermit the application of a sealing agent to the formation. In drillstem testing, they serve to isolate the strata to be tested so that anuncontaminated sample of the fluids contained therein can be recovered.In well completion operations, they are often used to direct theproducing fluids into an inner string of tubing in the wellbore. In wellstimulation processes, they are utilized to confine the stimulationfluid to the oil-bearing strata. In secondary recovery operations, theymay be employed to direct displacing agents or hot gases into the properstrata in a reservoir. Many other applications might be cited.

The packer assemblies utilized heretofore generally fall into twoclasses, inflatable packers and mechanicallyactuated packers. Theinfllatable devices are those which are set into place Within theborehole or wellbore by filling them with fluid through an orifice inthe drill string or tubing upon which the packer assembly is mounted.Devices of this type necessitate the use of the drill pipe or tubing toconvey the fluid to the packer and require that a valve and mechanismfor operating it be provided to open and close the orifice at the propertime. The mechanically-actuated packer assemblies generally depend uponthe placement of slips and rotation of the drill string or tubing, thedownward movement of the string or tubing against a member bearing onthe bottom of the borehole or wellbore, or upon similar movementcontrolled from the surface. The apparatus required to set such packersis often complex and may occupy considerable space in the wellbore orborehole. In some cases, release of the packers after they have been setpresents problems. Certain types cannot be released from the surface andmust be drilled out, making their use expensive if they are not to beinstalled permanently. For these reasons, neither type of conventionalpacker has proved wholly satisfactory in all applications.

The present invention provides an improved type of packer for use incertain oil field operations which is free of many of the disadvantagesassociated with inflatable and mechanically actuated packers employed inthe past. In accordance with the invention, it has now been found thatmovement of a bimetallic element in response to a change in thetemperature within a borehole or wellbore can readily be utilized to setand later release a packer without the necessity for hydraulic ormechanical control from the surface. This permits the use of packerswhich are considerably simpler in construction and operation than thoseutilized heretofore and facilitates the carrying out of many operationsrequiring the use of a packer.

The improved thermodynamic packer assembly provided by the inventionincludes a supporting structure capable of being mounted upon a drillcollar, tubing section, wellbore heater or similar device positioned ina borehole or wellbore, a bimetallic element which will move withrespect to the supporting structure under the influence of a change intemperature, and a sealing element for closing off the annular space inthe borehole or wellbore around the supporting structure in response tomovement of the bimetallic element. The supporting structure utilizedwill depend largely upon the character of the device upon which it is tobe mounted and may be varied considerably. A variety of bimetallicelements may be used. Obviously, the temperature conditions under whichthe packer assembly is to be set in the borehole or wellbore will beimportant in determining the bimetallic element to be employed. Thesealing element will preferably be a flexible member of rubber, plasticor asbestos but the material utilized, as well as its arrangement on thesupporting structure, will be governed to a large extent by theconditions in the wellbore or borehole and by the bimetallic elementused.

The exact nature of the invention and its objects can be best understoodby referring to the following detailed description of a number ofapparatus embodiments and to the accompanying drawings, in which:

FIG. 1 is a vertical section through a thermodynamic packer assemblyincluding bimetallic expansive elements positioned in a wellbore for usein conjunction with an in situ combustion operation;

FIG. 2 depicts the apparatus of FIG. 1 with the packer assembly set inthe wellbore;

FIG. 3 is a cross section through the apparatus of FIG. 2 taken alongthe line 3-3;

FIG. 4 is a vertical view, partially in section, showing a wellboreheater provided with a packer actuated by bimetallic elements inaccordance with the invention;

FIG. 5 is a vertical section through a thermodynamic packer employing adifferent type of bimetallic expansive elements; and

FIG. 6 is a cross section through the packer of FIG. 5 taken along theline 6-6.

Referring now to FIG. 1, reference numeral 11 designates casingpositioned in a wellbore drilled into a multizone oil reservoir, thelower zone of which has been partially depleted by primary productiontechniques and is to be subjected to an in situ combustion secondaryrecovery process independently of the upper producing zone. The casinghas been perforated opposite the lower producing zone of the reservoir,the perforations being indicated by reference numeral '12. The upperproducing zone and the corresponding perforations in the casing oppositeit are not shown in the drawing. The gases injected into the lower zoneto initiate and support the combustion process are tranmitted throughtubing 13 suspended within casing 11.

Packer support .14 is mounted at the lower end of tubing 13 just abovethe producing zone into which the hot gases required to initiate in situcombustion are to be injected. The supporting member is attached to thetubing by threads 15 or other suitable connecting means. The bore 16 ofthe supporting member forms an extension of the conduit in tubing 13 andhence fluids transmitted downwardly through the tubing emerge beneaththe assembly adjacent the perforations 12 in casing 11. The outersurface of member 14 contains an annular groove 17 in which theexpansive element 18 and the sealing member 19 employed in thisembodiment of the invention are carried.

Expansive element 18 consists of a plurality of bimetallic stripsatfixed at one end to supporting member 14 and extending radiallytherefrom at a downward angle in cantilever fashion. Each strip consistsof two metals having different coefficients of thermal expansion. Themetals making up the strips are bonded together and, as arranged in theapparatus of FIG. 1, the metal having the higher coefficient ofexpansion is placed on the lower side of each strip. The strips arepreferably, trapezoidal in shape and fit closely together when in theunexpanded position shown in FIG. 1. The arrangement of the strips onsupporting member 14 can be seen more clearly in FIG. 3 of the drawing.

Bimetallic strips 18 may be prepared from a variety of different metals,so long as the particular metals used have different coefiicients ofthermal expansion. By properly selecting the metals and by controllingthe dimensions of the strips, the expansion which occurs for a givenchange in temperature can be regulated. The metals employed should, ofcourse, have melting points well above the temperatures at which thepacker assembly is to be utilized. Metals which may be employed invarious combinations include iron, nickel, copper, aluminum, zinc,manganese, tin, lead, tungsten, chromium and the like. Alloys may alsobe employed. Two alloys particularly suitable for use as the high andlow expansive sides of a bimetallic element intended for use under hightemperature conditions are as follows:

Low-Expansive Side Studies have shown that a cantilever strip made up ofthe two alloys described above measuring three inches long andone-sixteenth inch thick will deflect about onehalf inch as itstemperature is increased from 200 F. to 600 F. Under the sameconditions, a strip three inches long and one-eighth inch thick willdeflect about one-fourth of an inch. This provides adequate movement forthe setting of the packer under high temperature conditions such asthose encountered in in situ combustion and similar operations. Otherbimetallic elements made up of different metals will move greater orlesser distances under different temperature conditions and hence thetemperature range over which the packer will set in place over aborehole or wellbore, as well as the degree of expansion which occurswith a given increase in temperature, can readily be controlled byutilizing the proper combination of metals.

Sealing member 19 is a flexible ring retained in notch 17 aboveexpansive element 18. It is preferred that the sealing element be madeof asbestos or similar heatresistant material in the case of packerassemblies intended for use at high temperatures such as thoseencountered in in situ combustion operations. Rubber or plastic sealingelements will generally be suitable for use in packers intended for lowtemperature operations. The outside diameter of sealing member 19 shouldbe such that expansion of bimetallic strips 18 will force it against thecasing or wall of the borehole in which the assembly is to be used. Itis preferred that the sealing member be sufiiciently thick that it willbe forced against the casing or borehole wall over a relatively largearea, thus assuring a good, fluid-tight seal. The material from whichthe sealing member or packer is made must be flexible enough that it canconform to irregularities in the casing or borehole wall. This isparticularly important in the case of packer assemblies intended for usein uncased wells.

In utilizing the apparatus shoWn in FIG. 1 of the drawing in an in situcombustion process of the type referred to heretofore, tubing 13carrying the packer assembly at its lower end is first lowered into thewellbore until the assembly is located just above the perforationscommunicating with the formation in which the in situ combustionoperation is to be carried out. Hot gases for initiating the combustionprocess, flue gases produced by burning a suitable fuel on the surfacefor example, are then passed downwardly through the tubing and assemblyinto the wellbore opposite the zone in which the combustion front is tobe established. Since these gases will normally be several hundreddegrees Fahrenheit above the ambient temperature in the wellbore, thetemperature of the bimetallic strips will rapidly increase. As thestrips expand due to this increase in temperature, they will forcesealing member 19 outwardly until a tight seal in the annular spacebetween casing 11 and supporting member 14- has been established. Thepacker is now set in place, as shown in FIG. 2 of the drawing. Thepressure built up as gas is injected into the space beneath the packeris exerted against the under side of scaling member and helps maintainthe seal. The injected gases flow into the formation throughperforations 12 and hence the heat necessary to initiate the combustionprocess is transferred to the formation.

Hot gases are normally injected into the formation during an in situcombustion process until the formation has been heated to a temperatureabove the ignition temperature of the oil present in the reservoir. Whenthis temperature is reached, the injection of hot gases is ordinarilyhalted and air, with or without inert gases, is supplied to theformation to support combustion and advance the combustion front. Atthis point, the bimetallic strips 18 on the packer assembly may begin tocool down and contract. Because of the high pressures utilized in suchcombustion processes, however, the pressure on the underside of sealingelement 19, not aflixed to bimetallic strips 18, will normally besuflicient to maintain the element in a distended position againstcasing 11. This pressure may range up to about 1500 pounds per squareinch or higher and hence it is preferred that the portion of supportingmember 14 above sealing element 19 be designed so that it will supportthe distended sealing member as shown in FIG. 2. Release of the pressureafter the bimetallic strips have returned to their unexpanded positionwill permit withdrawal of the apparatus from the borehole or wellbore.

It will be seen from the foregoing that the thermodynamic packer of theinvention provides a useful tool for controlling fluid circulation in aborehole or wellbore during a secondary recovery process utilizing insitu combustion. The packer assembly described in conjunction withFIGURES 1 through 3 of the drawing is not limited to the specificprocess described above, however, and will find application in a numberof other operations wherein changes in the wellbore temperature occur.It may be used equally well in conjunction with in situ combustionprocesses initiated by the reaction of pyrophoric materials such aslinseed oil and cobalt naphthenate in the presence of air or similaroxidizing agents. It may be employed in conjunction with wellboreheaters used for well stimulation, dehydration of swelling clays andother purposes. It can be utilized in connection with steam and hotwater injection processes employed for secondary recovery. It may findapplication for controlling the flow of the combustion gases at theproducing wells during in situ combustion operations. It can be used inwaterflood secondary recovery operations to direct the Water to theproper zone in a wellbore drilled through a multizone reservoir. In thiscase, the bimetallic strips will be arranged With the metal having thehighest coefficient of thermal expansion on the outside so the coolingeffect of the injected water will cause contraction and outward movementof the bimetallic strips to set the packer. When the device is utilizedin conjunction with a wellbore heater as mentioned above, the cantileverbimetallic strips and sealing element will generally be positioned onthe outer surface of the heater above the heating element therein. Theheater itself thus serves as the supporting structure.

FIGURE 4 of the drawing depicts a heater provided with a packer actuatedby bimetallic elements in accordance with the invention. As shown inFIGURE 4, heater 32 has been lowered within casing 33 to a pointopposite perforations 34 by means of self-supporting electrical cable35. The cable is affixed to the heater and is connect-ed to an internalresistance element not shown. Bimetallic strips 36, similar to thosedepicted in FIGURES 1 through 3 of the drawing, are Welded. bolted orotherwise aflixed at one end to the outer surface of the heater abovethe heating element. The strips are arranged in cantilever fashion sothat an increase in the temperature of the heater will result inmovement of the lower ends of the strips outwardly away from the heater.An annular sealing element 37 of asbestos or similar flexible,heat-resistant material is mounted on the outer surface of the heaterabove the bimetallic strips and is held in place by annular member 38which may be welded or otherwise bonded to the outer surface of theheater. When the heater is energized, sealing element 37 is forcedoutwardly into contact with the borehole casing to effect a seal. Thepacker of the invention may thus be utilized with a variety ofconventional Wellbore heaters of the electrical or combustion type. Suchheaters are available from a number of commercial sources and will befamiliar to those skilled in the art.

A further embodiment of the invention in which bimetallic elements arearranged upon the supporting structure in a somewhat different mannerfrom that described above is shown in FIGURES 5 and 6 of the drawing.Referring to FIG. 5, reference numeral 20- designates the lower end of asection of production tubing positioned within casing 21 in a wellbore.Fixed on the outer surface of tubing 20 is upper supporting member 22 towhich bimetallic strips 23 are attached at their upper ends. The uppersupporting member is preferably a ring welded or otherwise attached totubing 20 as indicated by reference numeral 24. Gasket inserts may beprovided between the ends of the strips on member 22, if necessary, toassure a fluid-tight seal between them. At their lower ends bimetallicstrips 23 are attached to lower supporting member 25 which is free toslide upwardly with respect to tubing 20, shoulder 26 on the tubingbelow the assembly preventing downward movement. The strips utilized maybe similar in composition to those described in conjunction with theprevious embodiment.

As shown in FIG. 6 of the drawing, bimetallic strips 23 are spacedevenly around the apparatus. Each strip curves outwardly from the upperand lower supporting members. The metal having the greatest coefficientof thermal expansion is placed on the outer face of each strip so thatthe strips will move out still further with increased temperature. Sincethe lower supporting element is free to move upwardly with respect totubing 20, the strips can expand without high stresses being set up.Flexible sealing element 27 made of rubber, asbestos, plastic or similarmaterial is positioned over the outer surface of bimetallic strips 23and is held in fluidtight relationship at the upper and lower ends ofthe as- 6 sembly by upper retainer 28 annd lower retainer 29,respectively. Bolts 30 and 31 or similar means are provided for holdingthe retainer, bimetallic strips and sealing element in place on thesupporting members. The sealing element is shaped to permit itsexpansion against the borehole or wellbore wall.

Operation of the apparatus depicted in FIGURES 5 and 6 of the drawing isgenerally similar to that of the previous embodiment. An increase in thetemperature of bimetallic strips 23 of the apparatus causes the stripsto expand outwardly, since both ends are constrained, forcing sealingelement 27 against the borehole or wellbore wall and effecting a seal.The temperature rise necessary to actuate the assembly can be controlledover a wide range by varying the composition of the bimetallic strips,by varying the length of the strips, and by varying the distance throughwhich the strips must move in order to force the sealing element into aclosed position. The use of relatively long strips positioned onsupporting members some distance apart permits considerable movementwith only a moderate temperature rise and hence this embodiment of theinvention may be preferred where very high temperatures are notutilized. Cooling of the device results in contraction of the bimetallicelements and retraction of the sealing elements so that the packerassembly can be withdrawn from the borehole, or wellbore.

The invention in certain aspects is particularly adapted to use inconjunction With in situ combustion operations and has been discussedprimarily from the standpoint of such operations. It will be apparent,however, that the thermodynamic packer assembly is not limited to insitu combustion processes and may be utilized in a variety of down-holeoperations where a packer must be set in place. In many instances itwill be convenient to combine the packer assembly with an electricalheating element or similar unit. Such a unit may be suspended on a wireline and may have the packer assembly mounted directly on the heater.Bimetallic strips arranged in spiral fashion around the supportingstructure may also be used. These and other modifications of theapparatus will readily suggest themselves to those skilled in the art.

What is claimed is:

l. A packer assembly comprising a supporting member which can be loweredinto a borehole; a plurality of bimetallic strips attached to the outersurface of said supporting member at points about the periphery of saidmember, each strip comprising two dissimilar metals bonded together toobtain outward deflection of said strip in response to a change intemperature; and a flexible sealing element mounted on said supportingmember in fluidtight relationship to said member, said sealing elementextending about said supporting member over the outer surfaces of saidbimetallic strips.

2. Apparatus as defined by claim 1 wherein said bimetallic strips areattached at one end to said supporting member and extend downwardlyabout said member.

3. Apparatus as defined by claim 1 wherein said bimetallic strips areattached to said supporting member with the metal having the greatercoeflicient of thermal expansion on the inner surface of each strip.

4. Apparatus for closing off the annulus of a borehole Which comprises atubular supporting member provided with means at the upper end forattaching said member to a string of pipe; a plurality of bimetallicstrips attached to the outer surface of said supporting member andextending downwardly about said member, each strip comprising twodissimilar metals bonded together to obtain outward deflection of saidstrip in response to a change in temperature; and a flexible annularsealing element mounted on said supporting member in fluid-tightrelationship to said member, said sealing element extending downwardlyabout said supporting member over the outer surfaces of said bimetallicstrips.

5. Apparatus as defined by claim 4 wherein an upper portion of saidsupporting member extends outwardly above said sealing element andlimits movement of said sealing element and said bimetallic strips withrespect to said supporting member.

6. Apparatus for closing off a borehole comprising a wellbore heatercontaining an electrical heating element; a plurality of bimetallicstrips mounted on the outer surface of said heater above said heatingelement, said strips extending downwardly about said heater and eachstrip comprising two dissimilar metals bonded together to obtain outwarddeflection of said strip in response to heat from said heating element;and a flexible sealing element mounted on said heater above saidbimetallic strips, said sealing element extending downwardly about saidheater over the outer surfaces of said bimetallic strips.

References Cited in the file of this patent UNITED STATES PATENTS1,998,915 Young Apr. 23, 1935 10 2,843,052 Andrus July 15, 19582,942,668 Maly et a1 June 28, 1960

